Lactic acid bacteria have been traditionally used in fermented food, also used in the manufacture of food and drink, medicines, probiotics and the like. Lactic acid bacteria have characteristics such as gram-positive, catalase-negative, not forming spore, immotile, and the like.
Lactobacillus paraplantarum (L. paraplantarum) is closely related to Lactobacillus plantarum (L. plantarum), and it has been known that L. paraplantarum and L. plantarum are non-pathogenic gram-positive lactic acid bacteria and are heterofermentative (Non-Patent Document 6).
Further, the entire genomes of some species and subspecies of lactic acid bacteria have been sequenced (Non-Patent Documents 1 and 2), and recombinant L. plantarum has been utilized for presenting a specific antigen through the epidermis of intestines and has been recently noted as a viable agent for preventing infection for oral administration (Non-Patent Documents 3 and 4).
On the other hand, it has been known that in a mechanism of innate immunity, immune cells such as macrophages and dendritic cells are responsive to substances activating innate immunity derived from bacteria or viruses to produce cytokines, thereby stimulating subsequent immune reaction. The mechanism of innate immunity is a mechanism for controlling infection that organisms have in common, is generally non-specific, has a good response, and effectively functions against many infectious sources.
In the past, the inventor has developed an evaluation method (a screening method) capable of easily measuring an activity for activating innate immunity, using silkworms having only a mechanism of innate immunity (Patent Document 1 and Non-Patent Document 5). In addition, the inventor has demonstrated that the evaluation method can evaluate or screen an innate immunity activator having activity for activating innate immunity against vertebrates such as humans (Patent Document 1, etc.).
Further, it has been demonstrated by the inventors that silkworms are useful as model animals of evaluating tolerance to infection caused by bacteria (Patent Documents 2, 3, etc.).
Abnormality of an immune mechanism causes various diseases. Thus, the development of an excellent innate immunity activator or agent for preventing or treating infection capable of adjusting such an immune mechanism has been desired. Further, the development of food and drink comprising material derived from lactic acid bacteria or the above agent, and food and drink utilizing the lactic acid bacteria having excellent characteristics has also been desired.